The invention relates to an apparatus and method for packing articles into cases using an apparatus and method having a continuous motion, and particularly, to improvements in article grippers for article depacking and packing, and improvements in a metering section for segregating successive slugs or groups of moving articles which are continuously picked up and transferred.
In the art of case packing, large numbers of articles must be grouped and packaged rapidly by an apparatus that will function dependably without damage to the articles processed. Case packing apparatus has been generally categorized as either intermittent case packing or continuous case packing. Most recently, attention has been directed to continuous case packing in order to increase production. However, the continuous case packing has brought increased problems with handling the processed articles without damage.
In the continuous case packing apparatus, articles conveyed in at least one row of articles are divided up into slugs or groups of articles which are fed to a pick-up position. The slugs of articles are picked up at the pick-up position by article grippers carried by an orbital handling conveyor. The slugs are transferred to a case loading position where the grippers release the slug of articles into a case. The articles can be released either simultaneously or sequentially as the case is conveyed beneath the slug of articles. Apparatus of this type may be either of the xe2x80x9cdrop packerxe2x80x9d type or xe2x80x9cplacement packer type.xe2x80x9d In the drop packer type, the articles are allowed to drop at least a small distance into the case after release. In the placement packer type, the drop, if any, is minimal and the articles are essentially placed gently onto the bottom of the case.
Various case packers, generally of the continuous motion type, using a vertical orbital conveyor are shown in U.S. Pat. Nos. 5,212,930; 4,541,524; and 4,294,057. The first patent shows depositing the articles sequentially and individually, rather than as slugs, into partitioned cases without positively gripping the articles. The latter two patents use gripper devices to grip the articles.
U.S. Pat. No. 4,457,121 discloses a continuous motion bottle packer wherein a plurality of grids are mounted individually on spokes of a vertical wheel so that each grid moves through an article infeed position where groups of articles are fed into the grid without interrupting the forward speed. The wheel moves the grids and articles to a lower discharge position where the groups of articles are dropped into a case without interrupting the motion of the articles in the direction of a case conveyor which indexes the cases. While continuous, this bottle packer generally of the drop packer type wherein the bottles are dropped into the case through resilient fingers. Also, a control problem is created due to the necessity of varying the speed between the rotating grids and the linearly moving cases in order to coordinate reliable timing of the grid and the case at the case packing position for reliable insertion of the slug. Angular and horizontal accelerations of the articles and their contents are also encountered due to the rotary wheel motion during the transfer which may be detrimental to the article and/or contents.
Continuous motion case packers are also known having a vertical rotating wheel which carries a plurality of arms which include two articulating links. A set of article grippers is carried on the ends of the articulating arms. The relative angular positions of the articulating links are controlled to place the article grippers over a slug of articles at a pick-up position, positively grip the slug, and lower the slug to a case packing position where moving cases are indexed with the moving gripper sets. However, during the angular descent from the pick-up position to the case packing position, both horizontal and vertical accelerations are encountered by the articles which are gripped only at their tops or necks. U.S. Pat. No. 5,313,764 discloses a continuous motion case packer wherein the articles and cases are indexed and conveyed on parallel conveyors arranged one above the other. Steering bars which correspond to the bars of a parallelogram move a gripper set, in the same general direction as the article and case conveyance, between the pick-up and case packing positions. However, again, horizontal and vertical accelerations are produced on the pick-up head and the articles, and timing becomes a problem.
Continuous case packers are also known in which a horizontal rotary carousel is used to move vertically reciprocating gripper sets in a horizontal plane. The reciprocating gripper sets pick up a slug of articles at one position and transfer the slug of articles to a second position where the gripper set is lowered to deposit the articles into a case. However, the disposition of the rotary carousel in a horizontal plane requires an inconvenient floor lay-out which also occupies a large amount of floor space. Typically, parallel conveyor arrangements are needed for the articles and the cases adding to the floor space problem. The path of the gripper sets between the slug pick-up position and the case packing position is also typically curved producing angular accelerations and forces on the articles, and the curved article path intersects the path of the conveyed case only for a brief interval. In various of the rotary carousel types, it is known to deposit the articles by lowering the articles, already gripped by the gripper set, through resilient fingers that guide the articles into partitioned cases.
Case packers, generally of the intermittent type, are shown in U.S. Pat. Nos. 3,553,932 and 3,505,787 which also disclose using combinations of a lifting head having suction cups and bottle grids having pockets for picking up containers and depositing them into cases. The containers and the cases are conveyed on parallel conveyors rather than in-line conveyors, and the transfer from the pick-up position to the case loading position is lateral, or transverse, to the flow of containers and cases. U.S. Pat. No. 2,277,688 discloses another case packer using an arrangement of a gripper set and a bottle guide set to package the containers into a case. These type of case packers are generally non-continuous as compared to the continuous motion in-line transfer case packers described above where neither the flow of articles nor the flow of the cases is stopped during operation of the packer.
Accordingly, an object of the invention is to provide an improved continuous motion case packing apparatus and method which can be used for case packing or depacking.
Another object of the invention is to provide a continuous motion apparatus and method in which slugs of articles are picked up, transferred, and deposited in a reliable, continuous manner without damage to the articles or their contents.
Another object of the invention is to provide a continuous motion case packing apparatus and method having a slug feeder which can be adjusted to change over the size of the slug in a quick and easy manner without the need of extensive machine down time and substitution and reassembling of mechanical parts.
Another object of the invention is to provide a continuous motion case packing apparatus and method in which slugs of articles are picked up and transferred to a case packing station over a horizontal linear transfer path in which the horizontal speed of the slug is constant, and depositing into a case is done in a gentle vertical motion.
Still another object of the invention is to provide a continuous motion case packing apparatus and method having a grid head which includes a matrix of gripper tubes which picks up articles from overhead, yet yields when an inverted article is engaged so that the remaining upright articles may be gripped and retained for transfer and deposit i a reliable and continuous manner.
Yet another object of the invention is to provide a continuous motion case packing apparatus and method in which a revolving carriage moves a plurality of transfer arms having reciprocating article pick-up heads in a vertical plane, closed curve path in a manner that the slugs of articles conveyed in the same plane are picked up, transferred, and deposited onto a conveyor in a reliable, continuous manner.
The above objectives are accomplished according to the present invention by providing a continuous motion apparatus for case packing or case depacking of articles. A carriage carries a plurality of transfer arms; and a plurality of article pick-up heads are carried by the transfer arms for picking up a slug of articles at a pick-up or release station for transferring the slug of articles for future processing.
In an advantageous form of the invention, the slug feeder comprises a slug metering section for continuously receiving articles from the infeed conveyor. A revolving pin bar mechanism is carried in the slug metering section having a plurality of revolving pin bar assemblies to assist in forming the articles into successive slugs of articles. The pin bar assemblies include spaced upstanding pins which are received in crevices between rear articles in a first slug and front articles in a second slug of articles to separate the articles into slugs for processing. A slug metering member is carried across the slug metering section which moves in and out of a path of conveyance of the articles in a cyclic manner in synchronism with said revolving pin bar mechanism. A metering distance is defined between the metering member and the revolving pin bar assemblies which determines the number of articles in a row and the size of the slug. A drive mechanism drives the metering member in the cyclic movements in and out of the article conveyance path. Preferably, the revolving pin bar mechanism includes a revolving mechanism; and each pin bar assembly includes a pin bar carrier pivotally carried by the revolving mechanism, a pin bar carried by the pin bar carrier, and the upstanding pins are affixed to said pin bar. Advantageously, a detachable mount detachably affixes the pin bar to the pin bar carrier so that the pin bar may be removed and a new pin bar may be affixed to the pin bar carrier having differently spaced pins for accommodating articles with different dimensions.
The detachable mount includes a first attachment element carried by the pin bar carrier and a second attachment element carried by the pin bar cooperating with the first attachment element for removably affixing the pin bar and pin bar carrier together. The upstanding pins are arranged in pairs on the pin bar and a distance between the pins in each pair corresponds to a dimension of the articles for effectively engaging and separating the articles into slugs.
In a further advantageous embodiment of the invention, the pin bar assemblies include at least one cam yoke carried by the pin bar carrier. An infeed cam plate is carried at an infeed end of the metering section having a first cam surface for engaging the cam yoke along a radial cam path. The cam plate has a second cam surface engaged by the cam yoke to move the pins from a first, non-contacting position to a second, contacting position wherein the pins are received in said crevices to contact the articles. A second cam plate cooperates with the first cam plate to define the radial path, and the second cam plate includes a third cam surface for urging the cam yoke toward the second cam surface of the first cam plate. A pair of vertically spaced top cam bars define a linear path along the metering section for guiding the cam yoke whereby the pins are positioned in a second position along the linear path. A bottom cam bar defines a bottom linear guide for guiding the cam yoke along a generally linear bottom path of the metering section. Preferably, the top cam bars comprise an upper cam bar and a lower cam bar, the upper cam bar prevents the pin bar assembly from rotating clockwise as the pin bar assembly contacts the article in the second position, and the lower cam bar prevents the pin bar from falling downwardly under the force of gravity. The cam yoke may be carried by a carrier arm of the pin bar carrier which secures the pin bar carrier to the flight bars, wherein opposing ends of the flight bars are secured to a drive chain of the revolving mechanism. The pin bar carrier is pivotally carried on the flight bar by means of the carrier arm to define a pivot, and the cam yoke is affixed to the carrier arm at a position which is displaced above and forward of the pivot relative to the direction of travel of the pin bar assembly so that proper pivotal movements are imparted to the pin bar assembly during slug separation.
In another aspect of the invention, when used as a packing machine, the metering member is carried by an adjustable carrier by which the metering distance between the metering member and the revolving pin bar assemblies may be adjusted to determine the number of articles in a row and the slug size. The drive mechanism includes a timing cam carried by the adjustable carrier for guiding the metering member in the cyclic motions which include reciprocating horizontal and pivotal motions. A first linkage is connected between the timing cam and the metering member for actuating the metering member in pivotal motions, and a second linkage connected to the timing cam and to the metering member for moving the metering member in linear movements. Preferably, the first linkage carries a cam follower which is received in a first cam slot of the timing cam, and the second linkage carries a cam follower received in a second cam slot of the timing cam. The first linkage comprises an actuator link connected by means of a pivot to the metering member for rocking the metering member up and down in cyclic motions; and the second linkage includes a reciprocating bar for reciprocating the metering member. The metering member advantageously comprises a metering bar extending across the metering section, and a plurality of upstanding posts arranged in spaced pairs carried across the metering bar, and the posts are rocked in and out of the path of the articles in cyclic movements for metering the number of articles in the slug.
In an advantageous embodiment of the invention for unpacking articles, a constant motion apparatus is provided for continuously transferring a slug of articles from a pick-up station to a release station. The apparatus includes a revolving carriage which carries a plurality of article transfer arms; and a plurality of article pick-up heads carried by the transfer arms which reciprocate in a linear motion relative to the transfer arms for picking up the articles at the pick-up station in the form of a group or slug of articles. A plurality of article gripper tubes is carried by each article pick-up head, and arranged in a matrix corresponding to the slug of articles. The gripper tubes having a grip position in which the articles are retained by the pick-up head at the pick-up station for transfer, and the actuator has a release position in which the articles are released from the pick-up head at the release station. The gripper tubes having a first effective axial length for picking up articles at the pick-up station when the articles are in an upright configuration, and the gripper tubes having a second effective axial length which is shortened relative to the first axial length for engaging an article at the pick-up station in an inverted configuration. An actuator is associated with the pick-up heads for actuating the gripper tubes between the grip and release positions. Preferably, the gripper tubes include a first part and a second part being axially movable relative to each other; and a gripper carried near an end of the second part. The first part of the gripper tubes may include a slip collar, and the second part includes an inner tube slidably received in the slip collar. Advantageously, a reciprocating mechanism is carried within the slip collar which acts as a solid member until an inverted article is engaged and the retracting mechanism is compressed. The retracting mechanism may include a spring assembly for biasing and maintaining the inner tube in the first axial configuration. For that purpose, the reciprocating mechanism may include a first spring which is in a compressed state when the gripper tube is in the second axial configuration. An article gripper is carried by the remote end of the gripper tubes which may include a second spring connected between the reciprocating mechanism and the grippers wherein the first spring rate is greater than the second spring rate so that the first spring mechanism acts as a solid elongated member until a sufficient load is placed on it which occurs as the gripper tube encounters the inverted article.